As used herein, the term “smoking article” includes smokable products such as cigarettes, cigars and cigarillos whether based on tobacco, tobacco derivatives, expanded tobacco, reconstituted tobacco or tobacco substitutes and also heat-not-burn products. Smoking articles may be provided with a filter for removing constituents from the gaseous flow.
Filters may be provided with an additive for modifying the smoke, such as a flavourant.
Filters may have movable elements for controlling the air dilution value, the resistance-to-draw and/or the amount of added flavourant in the smoke stream. However, filters with movable elements are generally complex and so expensive to manufacture or do not provide a very satisfactory smoker experience.